Our CNC-porting of GM LT heads significantly improves airflow of these heads. The stock LT heads are known to have valve guide wear issues. We replace the factory guides with CHE valve guides made from CHE's proprietary bronze alloy. This extends the heads' longevity.
We know what makes power and also survives the beating of competition. It's not chasing peak air flow at max lift by excessively cutting away the metal around the valve guides. Peak air flow occurs at only one instant in the cycle. Our focus is more on average air flow across the entire cycle. For spring packages with 0.650 inch max-lift, quoting a peak airflow at 0.800 inches is irrelevant.
Of paramount importance for us is that our heads don't break and wreck our engines. We therefore do not chase flow at the expense of weakening the heads mechanical integrity. That's a concern that non-engine builders don't share.
We will disassemble and clean your heads upon arrival. Our process for machining these heads starts with CNC porting on our 5-axis. This is followed by CNC valve jobbing and bowl blending in a single operation on our Newen CNC seat & guide machine (see video down below).
The air flow results we get are as shown in the Table immediately below.
Valve Lift: 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.75 0.8
Intake: 91 160 240 297 335 358 375 382 382
Exhaust 69 126 180 198 221 236 246 249 249
Intake Valve: 2.126"
Ex Valve: 1.590"
After Intake: 296cc
After Exhaust: 110cc
Max Lift 0.65"
Chamber Vol. 65.5cc
The heads are then reassembled with your original hardware (if useable), or with the optional parts as discussed in the next paragraph.
We offer a variety of optional valve & spring packages for these heads. Our standard spring & valve package comes with GM titanium intake and Manley stainless steel exhaust valves. These are paired with a BTR dual spring kit and titanium retainers. A variety of other hardware options are available. Click BUY NOW for options pricing.
Call us at 815-725-2727 to discuss your requirements. Pricing is per pair. Shipping charges are not included.
NOTE & DISCLAIMER: GM LT heads have a known issue of dropping valves seats, particularly under extreme conditions. While rare, any such occurrence will cause serious or irreparable damage to the engine. Borowsi Race Engines, Inc. disclaims any responsibilty for such issues as these would be GM factory defects. We offer our CID CNC-ported LT4 heads as an alternative. These are particularly recommended in race applications.
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